app/views/mtdevise/account/users/new.html.erb
<h2>Sign Up</h2>
<%= form_for(@user, :url => do_user_sign_up_url), html: {class: 'form-vertical multiple_tags', role: 'form'} do |user| %>
<%= render 'shared/validation', object: user.object %>
<%= render "mtdevise/account/users/form", :user => user %>
<%= user.submit "Sign Up", :class => "btn btn-primary" %>
<% end %>